Myofascial stiffness of plantar fascia and Achilles tendon in individuals with plantar fasciopathy: An observational cross-sectional study

Background: Assessment of myofascial tissue stiffness have a role in identifying physical impairments in plantar fasciopathy (PF). It is still unclear which specific functional and tissue differences exist between individuals with PF. Aim: To compare myofascial stiffness of plantar fascia, Achilles tendon, and triceps surae between symptomatic and asymptomatic limbs in individuals with PF and between individuals with and without PF. Methods: Thirty nine individuals diagnosed with PF and individuals with no history of PF were recruited. Myofascial stiffness of the plantar fascia, Achilles tendon, and triceps surae, range of motion, and clinical tests were performed. Mean difference (MD) and 95% confidence interval (CI) were calculated. Results: Individuals with PF showed lower mean stiffness in Achilles tendon insertion (MD = -1.00 N/mm; 95% CI: 1.80,-0.21) on the symptomatic limb compared to the corresponding symptomatic limb in control group, a lower mean stiffness in plantar fascia (MD = -0.16 N/mm; 95%CI: 0.30, -0.01) on the symptomatic limb compared to asymptomatic limb, and a lower mean stiffness in the region 3 cm above the Achilles tendon insertion (MD = -0.79; 95%CI: 1.59, -0.00) compared to control. Individuals with PF showed fewer repetitions in heel rise test (MD = -3.97 reps; 95%CI: 5.83, -2.12) and in the step-down test (MD = -5.23 reps; 95%CI: 7.02, -3.44) compared to control. Conclusions: Individuals with PF present reduced stiffness in Achilles tendon insertion and plantar fascia. The reduced stiffness was more evident in Achilles tendon in individuals with PF compared to individuals without PF. Individuals with PF showed lower performance in clinical tests.